A lullaby, or a cradle song, is a soothing song or piece of music that is usually played for children. The purposes of lullabies vary. In some societies, they are used to pass down cultural knowledge or tradition. In addition, lullabies are often used for the developing of communication skills, indication of emotional intent, maintenance of infants' undivided attention, modulation of infants' arousal, and regulation of behavior. Perhaps one of the most important uses of lullabies is as a sleep aid for infants. As a result, the music is often simple and repetitive. Lullabies can be found in many countries, and have existed since ancient times.

"Silent Night" is a popular Christmas carol, composed in 1818 by Franz Xaver Gruber to lyrics by Joseph Mohr in Oberndorf bei Salzburg, Austria. It was declared an intangible cultural heritage by UNESCO in 2011. The song was first recorded in 1905 and has remained a popular success, appearing in films and multiple successful recordings, as well as being quoted in other musical compositions. It is the world's most recorded Christmas song, with more than 137,000 known recordings.